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(No Model.) 2 Sheets-Sheet 1.

H. B. NILES & J. B. FORD. PROCESS OF TREATING PLATE GLASS.

I No. 433,254. Patented July 29, 1890.

' INVENTOI? fi arzy E, .A ZZe 5 W/TNESSES:

(No Model.) 2 Sheets-Sheet 2.

H. B. NILES & J. B. FORD. HOURS OF TREATING PLATE GLASS.

No. 433,254 Patented July 29, 1890.

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V I I ATTORNEY.

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' UNITED STATES PATENT OFFICE.

HARRY B. NILES, OF INION SPRINGS, NEYV YORK, AND JOHN B. FORD, OF

CREIGHTON, PENNSYLVANIA.

PROCESS OF TREATING PLATE-GLASS.

SPECIFICATION forming part of Letters Patent No. 433,254, dated July 29, 1890. Application filed January 25, 1890. Serial No. 338,137. (No model.)

To all whom it may concern: The invention consists, csse1'1tially,in plac- Be it known that we, HARRY B. NILEs and ing the translucent plate upon or against a JOHN 13. FORD, citizens of the United States, metallic plate or plates, and passing such a residing at Union Springs, in the county of current of electricity through the latter as 55 Cayuga and State of New York, and Creighwill heat the glass plate from 7 00 to 900 ton, in the county of Allegheny and State of Fahrenheit. At these temperatures the glass Pennsylvania, respectively, have invented plate will soften, thus dissolving the chill certain new and useful Improvements in the and rendering the plate again transparent. Process of Treating Plate-Glass, of which the To get the best product it may be necessary 60 following is a specification. to grind and polish the plate slightly; but Our invention relates to the manufacture by this heating process the chill is removed, of plate glass. Its object is to provide means thus eliminating thelengthy grinding process and a process for treating the glass to render and,furthern31ore, turnin goutaproduct which it transparent after the-first rolling, In is of considerable value. Electricity is par- 65 the ordinary manufacture of plate glass a ticularly adapted for heating the plates, be-

billet of molten stock is taken from the furcause by it a uniform temperature over the nace and placed upon a cold metallic plate whole plate may be obtained, and the same called the casting-table. A cold roller is may be regulated at will. This cannot be acthen passed over it, which makes it into the complished with gas-jets or other similar heat- 70 form of a plate and of the required thickness. ing apparatus.

This cold-rolling process, however, forms a The apparatus for carrying out our inventhin skin of rough glass on each side of the tion is illustrated in the accompanying drawplate, which takes from the plate its transings, in which parent quality and renders it translucent. Figure 1 represents a diagram of the elec- 75 2 5 This thin skin of rough glass is called the trio circuit and a metallic heatingplate chill, and is caused by reason of the table mounted upon a truck in the usual manner. and roller being cold. It is necessary that Fig. 2 is a plan of a heating-plate, showing the table and roller be cold, for if they were connections of electrical conductors for getanywherenear the temperature of the molten ting an even heat over the plate. Fig. 3 is 80 0 glass the glass would stick to them and prea diagram of the circuits when an induction vent effective work. The glass after being coil or converter is used. Fig. 4: is a plan of rolled is placed in the annealing-oven, and a modified form of plate, and Fig. 5 a reprethere subjected to a slow process of cooling, sentation of mechanism for confining the after which it is ground and polished. Thus at plates under pressure while undergoing the 85 3 5 no time during the process is the glass transheating operation.

parent until polished. It is thus impossible A represents a metallic plate or table, uponto produce by this process more than one which the glass is placed after it has been grade of transparent glass, and that grade subjected to the first rolling. This plate is must be polished platerglass. supported upon a truck, so that it may be 0 Our invention is designed to facilitate the easily moved about the works in the. different process of rendering the plate transparent stages of manufacture. The plate of glass is after the first rolling by removing the rough represented by B and is placed flat upon the chill, thus producing a cheap grade of trans plate A. This having been done, the plateA parent plate glass, for which we think there is connected in a'circuit C, over which flows 5 is a market. To also intend to introduce a current of electricity from a generator 0.

this treatment into the ordinary process by The circuit also includes an adjustable rheoremoving the chill, as hereinafter described, stat D, by means of which any quantity of and then grinding the surface smooth. Ordicurrent desired may be allowed to flow through narily the surface is not only ground smooth, the plate. The resistance which the plate 10c, but the entire skin or shell is taken off,which offers to the current will cause it to become is a very slow and expensive operation. heated, and through the rheostat the temperature may be raised as fast as necessary until the softening-point of the glass is reached, which is from 700 to 900 Fahrenheit. The softening of the glass causes the translucent skin to disappear and leave the plate in a fairly good transparent state. The product thus obtained is adapted to many uses. To produce the best quality, however, it may be necessary to grind and polish the plate a little; but the extent of this grinding and polishing operation is very small compared to the amount necessary after the ordinary process.

By branching the electrical conductors where they make contact with the plates, as shown in Fig. 2, the current is evenly distributed over the plate and therefore heats the plate uniformly.

In Fig. 3 a converter or induction-coil E is placed in the circuit and an alternating or pulsating generator used. lVith this arrangement a large current with low voltage may be obtained, and consequently the heating effects of the current may be increased.

Fig. 4 shows the metal plate, provided with a series of slits or kerfs on each side, the slits of the two series alternating with one another and extending nearly but not quite across the plate. The slits may be filled with fire-proof insulating material or may be left open, the air-space forming sufficient insulation. By this construction the sectional area of the path of the current may be increased or diminished, as desired, thus making the resistance whatever is desirable regardless of the size or thickness of the plate. The plates will therefore not require so much current to raise them to a given temperature. It is intended to file a separate application for this form of plate and claim it as a rheostat. Specific claims are therefore not made in this case for it.

In Fig. 5 we have shown the metallic heating-plate placed between two glass plates and the three then clamped in a press. This may not be utilized in the process; but it will prevent warping, if it becomes necessary.

It will now be understood that in carrying out our invention we place the glass plate in contact with a heating plate or table after it has been treated to the ordinary rolling between cold surfaces, and by passing a current of electricity through the said heatingplate the resistance of the latter is such that a sudden heating of the surface or chill of the glass can be attained, which results in softening it without unduly heating the remainder or body of the glass.

We are aware that it is not new to reheat glass plates after they have been rolled between cold surfaces; but to place such glass plates in contact with a metallic plate and then raise the temperature of the latter by means of an electric current passed through it possesses the advantage of enabling the surface or chill of the glass to be fused or softened without unduly softening the body of the glass, and in this our invention broadly consists.

Having thus described our invent-ion, we claim 1. The process of man ufacturi ng plate-glass herein described, which consists in first rolling the molten glass into a plate, then placing the glass plate in contact with a heating plate or table, and raising the temperature of the heating plate or table by passing an electric current through it until the glass plate softens.

2. The process of making translucent plateglass transparent, consisting .in heating the translucent glass plate until it softens by bringing it into contact with a metal plate or plates heated by electricity.

3. The combination, with a casting plate or table used in glass-making, of a generator of electricity, and an electric circuit including said generator and said casting-plate.

4. The combination, with a casting plate or table used in glassanaking, of a generator of electricity, and an electric circuit including said generator, a rheostat, and said castingplate.

In witn css whereof we have hereunto affixed our names in the presence of witnesses.

HARRY B. NILES. JOHN B. FORD.

Witnesses as to Niles: JAMES KENT, ALLEN OooK.

Vitnesses as to Ford: W. H. CAMP,

J. C. F. LARDIN. 

